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The majority of Mountain Coal Company's hydrologic monitoring <br />concentrates on mine water dischazges and wells associated with B-Seam <br />mining. Disturbances and changes to water quality, if they occur, will be <br />manifested in B Seam discharge water and B Seam monitoring wells <br />prior to any potential impacts to the Rollins Sandstone. The B Seam is <br />sepazated from the Rollins by siltstones, shales, and another coal seam. It <br />is unlikely that the Rollins Sandstone would be used as a primary <br />drinking water source because of its great depth outside stream valleys, <br />its existing low yield and poor water quality and the ready availability of <br />better quality surface water near the stream valleys. <br />MCC has mapped the B Seam overburden thickness with potential areas <br />of groundwater inflow highlighted. These areas of potential inflows, <br />similar to the F Seam, are associated with fracture zones beneath <br />drainages and neaz outcrops and azeas of low overburden. A map of the <br />potentiometric surface of the B Seam has been produced and can be <br />reviewed in Exhibit 17A and figure 7F of the permit document. <br />MCC has made inflow estimates for the B Seam mine plan. The <br />"probable maximum" estimate of mine inflow shows a peak or initial <br />inflow rate of about 150 gallons per minute (gpm) and a longer term <br />steady rate of about 100 gpm. Recent experience shows that mine <br />inflows have the potential to be much higher, at least for short periods of <br />time, as indicated by measurement of inflows of as much as 2,500 gpm <br />encountered in April 1996 while mining through afault/fracture system <br />in the B Seam. <br />An estimate of mine inflow for the projected life of mine was also <br />completed. This case showed a long term steady inflow rate of about 85 <br />gpm. Maximum inflow is estimated to be 100 gpm. The time-to-fill <br />calculation for the B-seam was 59 years. <br />The B Seam mine will not cause significant hydrologic impacts to <br />groundwater systems in the five-year permit area based on the data <br />provided. <br />The majority of springs are located at or above the F Seam outcrop. A <br />few springs have been identified between the E and F Seam outcrops. No <br />springs have been identified below the E Seam outcrop. Only three small <br />ephemeral springs occur in the West Flatiron azea and these springs <br />should not be affected by mining in the B-seam. <br />Monitoring of springs for baseline data and to assess impacts of mining <br />in the F Seam has been carried out for more than twenty years by MCC. <br />Evidence to date indicates that mining has very little, if any, impact on <br />spring flows. <br />54 <br />